Conversion shield for mask window



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United States Patent 3,147,487 CONVERSTON SlHELD FOR MASK WINDQW EdwardL. Hoeftinan, Pittsburgh, Pa., assignor to Mine Safety AppliancesQompany, Pittsburgh, Pa, :1 corporation of Pennsylvania Filed Nov. 7,1962, Ser. No. 235,963 1 Claim. (Cl. 2-8) This invention relates tobreathing masks, and more particularly to means for converting them intowelding masks of abrasive masks.

The mask shown in Patent 2,956,474 is provided with a large windowsurrounded by a bead, in which the edge of the window is sealed. Thepatented mask is intended for protection in noxious atmospheres. Thereare times when the wearer or owner of such a mask may wish to do somewelding or abrasive cleaning with a loose grit. In such cases he mustacquire an additional mask for welding or abrasive use, either for usealone or for application over his gas mask, depending on whether or nothe is to work in fresh air. This not only adds to his expense, but

where one complete mask or shield must be used over another mask anawkward situation is created.

It is among the objects of this invention to provide a simple andinexpensive device for application at will to a breathing mask in orderto shield the window of the latter from intense light or abrasives sothat the mask can readily be converted into a welders mask or anabrasive mask.

In accordance with this invention, a face plate is shaped to fit thefront of a breathing mask that is provided with a window surrounded by ahead. The face plate is provided with a central opening in front of thewindow. Extending across this opening is a protective screen, which canbe a colored glass for screening out intense light rays or a wire screenor cover glass for protecting the mask window from abrasive particles.The screen is connected to the face plate, preferably through a specialhinge. Attached to the face plate are supporting means, such as hingedclips, for detachably connecting the plate to the bead around the maskwindow so that the shield is supported and carried by the mask.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a front View of a breathingmask provided with my conversion shield;

FIG. 2 is an enlarged fragmentary horizontal section taken on the line11-11 of FIG. 1;

FIG. 3 is a side view of the mask and shield with parts broken away invertical section; and

FIG. 4 is an enlarged fragmentary vertical section through one of thehinges, showing the protective screen raised out of the line of vision.

Referring to the drawings, the front of a gas mask 1 or the like isprovided with a large opening surrounded by I an integral bead 2. Theinside of the bead is provided \with a groove 3, in which the edge of aglass window 4 is 1 ounted. Preferably, the window is curvedtransversely for better lateral vision. To seal the edge of the windowin the bead, the opposite sides of the latter are compressed against thewindow by any suitable means, such as a metal clanitping channel 5fitting around the bead.

It is a feature of this invention that this mask can be converted into awelders mask. This is done by a conversion shield for the mask window toprotect the window and reduce the intensity of the light from a weldingtorch. The body of the shield is a face plate 7 that is shaped to fitthe front of the mask around its window. The plate is provided with alarge central opening 8 in front of the window. The wall of the openingis rectangular and extends forward into a flat upright plane. Aprotective screen extends across the front part of opening 3. When3,147,487 Patented Sept. 8, 1964 the shield is to be used for welding,the screen includes a dark colored glass plate 9, in front of whichthere may be a thin cover glass 10 to protect it. These plates aremounted in the internal channel 11 of a rectangular frame 12 thatengages the front of the face plate opening wall and extends back intothat opening. The two pieces of glass may be pressed forward against thefront of the frame channel in a well known way by a bent wire 13compressed between the back of the channel and the back of the coloredglass. The screen frame is supported from the top of the face plate bymeans of hinges so that the frame can be swung up out of the line ofvision whenever desired.

In accordance with this invention, the face plate can be quickly andeasily attached to the mask by means of U-shape clips 15, the outer endsof which are connected by hinge pins 16 to forward projections 17 on theplate. Preferably, there are at least two clips at each end of the faceplate. The rear ends of the clips are adapted to be swung back behindthe mask bead to clamp the face plate in place. To form a secureconnection and to seal the space between the face plate and mask bead 2,it is best to attach a resilient cushion ring 18 to the marginal area ofthe back of the face plate in a position to engage the front of the maskbead. This cushion ring is thick enough to require it to be compressedsomewhat for the clips to be swung into engagement with the bead, andtherefore the ring will hold the clips tightly in place.

Freferably, there are two laterally spaced hinges supporting frame l2,each of which includes a lug 20 extend ing upwardly from the frame andsupported at its upper end by a hinge pin 21 having ends mounted in apair of lugs 22 projecting forward from the front of the face pieceabove opening 8. Another feature of this invention is that a block 23,which contains resilient material, is com pressed between the back ofeach frame lug and the face plate behind it, as shown in FIGS. 3 and 4.Preferably, the block is disposed in a socket 24 formed in the platebetween its lugs 22. The block is most suitably made from a thick pad 25of rubber or similar resilient material, the front surface of which iscovered by a flat relatively stiff spacer 26 cut from a thin strip ofnylon or other hard surface material. This spacer is pressed forwardagainst the back of the lug by the resilient pad, which is always undercompression. The pressure is great enough to hold the screen framefirmly against the face plate.

When the user swings the frame up to its upper position as shown in FIG.4, the resilient blocks will continue to press against its lugs Ztl,which are so shaped that they will have to compress the blocks stillmore in order for the frame to swing down to its lower position again.The pressure of the blocks against the lugs is great enough to hold theframe in its upper position until it is swung down manually. The shapeof the frame lugs required for holding the frame in either of its twopositions is produced by extending their free ends, which are locatedbetween the lug areas that are engaged by the resilient blocks in thetwo positions of the frame, a greater distance than those areas awayfrom hinge pins 21. Consequently, in order for the frame to be swungfrom either position to the other, the projecting free ends of the lugsmust compress the blocks more than they otherwise are compressed. Theresistance of the blocks to such further compression is what holds theframe in either position to which it has been swung. Spacers 26 servetwo purposes. They help distribute the pressure of the frame lugs moreuniformly over the rubber pads, and they form smooth hard surfaces forthe ends of the lugs to slide against as the screen frame is swung up ordown. Otherwise, there would be the danger of the lugs sinking into thepads and pushing them up or down in sockets 24.

a I a a If it is desired to protect the mask window from the grit usedin abrasive cleaning, a conversion shield can be used in which a clearglass plate is substituted for colored glass 9, and cover glass 10 isreplaced by a wire screen.

It will be seen that with this invention a simple, lightweight, smalland inexpensive shield can be quickly and easily attached to a gas maskor the like to adapt it for use as a Welders mask or a mask for use inabrasive cleaning.

I claim:

The combination with a mask provided with a transversely curved Windowhaving convex edges at opposite sides of the mask, the mask also beingprovided with an integral bead surrounding the window and grooved toreceive its edge, of a conversion shield comprising a face plate fittingthe front of the mask around said window and provided with a centralopening, a protective screen extending across said opening, meansconnecting the screen with said plate, clips hinged to the ends of theface plate and having free ends hooked behind the mask bead, and aresilient cushion ring secured to the marginal area of the back of thefaceplate and engaging the front of said bead, said ring beingcompressed between the plate and bead to thereby hold said clips tightlyagainst the back of the bead, and said clips being manually swingableaway from said bead to release said shield from the mask.

References Cited in the file of this patent UNITED STATES PATENTS1,060,083 Harris Apr. 29, 1913 2,031,676 Shindel Feb. 25, 1936 2,129,250Varker Sept. 6, 1938 2,411,224 OReilly Nov. 19, 1946 2,590,526 EvansMar. 25, 1952 2,741,398 Riener Apr. 10, 1956 3,016,543 Lindblom Jan, 16,1962

